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By Elise Labott and Tom Cohen

CNN

KIEV, Ukraine (CNN) — Secretary of State John Kerry forcefully denounced Russia for trying to create a pretext to further invade Ukraine, and he pledged U.S. commitment to Ukrainian sovereignty and territorial integrity after announcing $1 billion in loan guarantees for the new government.

The United States “will stand by the Ukrainian people,” Kerry told reporters in Kiev after accusing Moscow of making up reasons for sending troops into the Crimea region based on alleged persecution of Russian speakers and native Russians.

“Not a single piece of credible evidence supports any one of these claims,” Kerry said, adding that it was clear “that Russia has been working hard to create a pretext to invade further” in Ukraine.

In Washington, President Barack Obama again denounced the use of force and said there is a strong belief around the world that Russia is violating international law.

“I know (Russian) President (Vladimir) Putin seems to have a different set of lawyers making a different set of interpretations but I don’t think that’s fooling anybody I think everybody recognizes that although Russia has legitimate interests in what happens in a neighboring state that does not give it the right to use force as a means of exerting influence inside of that state,” Obama said.

Kerry said the United States prefers for Russia to de-escalate the crisis, but if that doesn’t happen, “then our partners will have absolutely no choice (but) to join us to continue to expand on steps we have taken in recent days to isolate Russia diplomatically, politically and economically.”

The loan guarantees will help Ukraine move forward with an assistance package from the International Monetary Fund, which is calling for the country to raise energy prices.

Kerry arrived Tuesday in the Ukrainian capital to show American support for the fledgling government.

While condemning the Russian show of force, which Kerry said was “not 21st Century, G8, major nation behavior,” he also offered a way out by calling for Russia to call troops in Crimea back to their barracks and allow international observers to monitor the situation.

Obama administration officials traveling with Kerry said Treasury Department technical advisers would travel to Ukraine to help its national bank and finance ministry deal with economic challenges and implement energy sector reforms.

The United States also will train observers for the May 25 elections, and is sending a team of experts to help identify stolen assets and support anti-corruption measures.

With Ukraine looking to reduce dependence on Russian energy, the United States will provide assistance and financing to help businesses find new export markets and will offer technical advice to the government on Ukraine’s World Trade Organization rights with respect to Russia.

The assistance package comes as the United States considers economic sanctions against Russia, which one of the officials said could come within “days, not weeks.”

The official spoke of a “solidification of Russian control of Crimea” and also referred to unconfirmed reports that Russian helicopters attempted incursions into Ukrainian airspace before Ukrainian planes chased them away.

In addition, the official discussed unconfirmed reports of forces massed on the isthmus separating Crimea from mainland Ukraine, sparking concern Russia wants to extend its forces to the Ukrainian mainland.

“We still have a very real concern that the Russians have other plans in Ukraine,” a second official said.

The officials emphasized the importance of de-escalating tension in the region and pointed to a diplomatic way out for Russia to address its concerns in Crimea through international monitors. The Organization for Security and Cooperation in Europe, a regional security bloc, sent in 10 monitors Monday, but the officials encouraged Russia to agree to a much larger observer mission.

Russia should also engage in a dialogue with Ukraine, the officials said. The United States hopes to convene a meeting of signatory countries of the 1994 Budapest Memorandum, a pact of security assurances signed by the United States, Britain, Ukraine and Russia — as early as this week to begin that dialogue, but the officials said such a meeting was not yet scheduled.

“There is a way out for Russia,” the first official said. “If Russia does not chose that off ramp, then the message from the administration is we are ready then to put in place more robust measures.”

CNN Foreign Affairs Reporter Elise Labott reported from Kiev and Tom Cohen from Washington.

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